Packing passengers onto planes may be good for airlines’ bottom line but for travelers the shrinking space is giving way to rancorous rides.

In just the last 11 days, flying travelers tussling over personal space, or the lack thereof, caused three U.S. flights to make unscheduled landings.

In one incident, a United Airlines passenger using a $21.95 gadget called the Knee Defender on a trip from Newark to Denver had a cup of water dumped on him when he refused to remove the device and allow his fellow traveler to recline. The jet was diverted to Chicago.

Three days later an American Airlines flight from Miami to Paris was disrupted when two passengers argued over a reclining seat and the jet was diverted to Boston. Then, on Sunday night, a woman resting her head on a tray table started to scream and swear when a woman tried to put her seat back. The Delta flight from New York's LaGuardia Airport to West Palm Beach was rerouted to Jacksonville, Florida.

Sara Nelson, president of the Association of Flight Attendants, told the Associated Press that seats are getting closer and that attendants have to constantly de-escalate conflicts. And, the end is not near. In fact, it appears to be getting worse. "The conditions continue to march in a direction that will lead to more and more conflict," Nelson said.

The space debate has people squaring off on both sides of the aisle, on jets and, of course, on Twitter.

Perhaps the most famous chair kerfuffle was in 2010 when former presidential candidate Mitt Romney was seated behind Skyler Gordy, aka, Sky Blu of the rap duo LMFAO. On an appearance on the David Letterman show Romney said he simply told the person in front of him to put his seat upright during takeoff. "So I tapped him on the shoulder and reminded him of that direction, and he didn’t like that, by the way, and he gave me a good swat and he broke my hair." ("Broke my hair? OK, I digress.)In his version of events, however, Sky Blu said he was sleeping when he was met with a hostile passenger sitting behind him who yelled at him and then grabbed his shoulder so he reacted. The incident apparently inspired LMFAO’s song "We Came Here to Party" which contains these lyrics: "We both get a lot of attention in the press. You sellin’ books and wanna be the president. We sellin’ hooks and the flow is heaven sent. We both hustlin’, so why we tusslin’?"

Why indeed? But not everyone thinks that leaning back in your seat is a rude thing to do.

Enter the Knee Defender. Billed as a travel gadget designed to protect flyers against "aggressive seat recliners" the plastic device hooks on seats and keeps chair backs from getting too close to one's personal space. Some think the gadget is a sign of the decline of Western civilization.

Weird how people keep saying "The Knee Defender" instead of "inability to connect on a human level anymore."

But others, like Damon Darlin of the New York Times, say that a device like the Knee Defender "reallocates property rights" and that using one does not make a person a jerk. Further, Darlin maintains that airlines could solve the problem by "declaring themselves Reclinists or Knee Savers, and passengers could choose which airline to fly based on that (or at least would know what to expect on board)."Can't you just see the ad copy for that? "Recline supine!" Or, "knees need not be kneaded!"